1. Technical Field
The present invention relates in general to inserting circuit cards into activated systems. In particular, the present invention relates to a method and system for preventing voltage arcing and dropout resulting from initial insertion of a circuit card into an activated system. Still more particularly, the present invention relates to a method and system for providing a voltage source from which circuit card input capacitance may pre-charge, thus preventing arcing and voltage dropout when the card is initially inserted into an activated system.
2. Description of the Related Art
Various systems and methods for the rapid insertion of electronic subassemblies, such as printed circuit boards into a computer chassis, are known in the art. Typical methods utilized to minimize the impact of plugging into a live electronic system generally address the disruption to the bus signals to which a subassembly is being attached. Disruption to the power supply subsystems and subsequent electronic problems that this disruption causes is not generally addressed other than by deactivating or otherwise removing the power source before insertion can be accomplished.
A method and system for controlled removal and insertion of circuit modules into a system bus is known from U.S. Pat. No. 4,835,737. According to the teaching of this document, the operation of the bus is inhibited during the period that a module is being inserted into a connector connected to the bus, and the bus is reactivated after the module has been inserted. Quiescing of the bus in this manner, however, does not address power supply disturbances. In addition, there is no simple way to manage peripheral component operation during the interruption. Also, since subsystems within a digital system are often asynchronous with respect to each other, sequential operation errors become a significant possibility.
The so-called xe2x80x9chot pluggingxe2x80x9d concept provides power interconnects to a live system without causing interruption of ongoing data transfers in the rest of the system. Hot plugging is utilized in fault tolerant systems which normally include device or field replaceable unit redundancy coupled through operational comparison and checking logic to ensure correct operation. Both the bus design and the control device must be carefully designed to achieve this xe2x80x9chot pluggingxe2x80x9d capability.
A representative system for facilitating hot plugging of circuit cards into activated electronic systems is described in U.S. Pat. No. 5,432,916, issued Jul. 11, 1995, to Hahn et al. The design described in this document, as well as other current hot plug protection designs, focus primarily on preventing transients to the extent that signal switching is not so adversely affected. Hahn et al. teach a system by which electrical transients resulting from hot plugging are reduced by managing the transient load on the driver of the port of the active system in which the electrical circuit is to be hot plugged. The management of transients is accomplished in part by staggering connection means at the input/output (I/O) ports of the electrical circuit and adding so-called xe2x80x9cpreconditioningxe2x80x9d impedance networks within the signal network of the circuit. This hot plug management technique, however, only addresses transients on the signal bus.
It is therefore one object of the present invention to provide an improved method and system for inserting circuit cards into activated systems.
It is another object of the present invention to provide a method and system for preventing voltage arcing and dropout resulting from initial insertion of a circuit card into an activated system.
It is yet another object of the present invention to provide a method and system for providing a voltage source from which input capacitance of a circuit card may pre-charge, thus preventing arcing and voltage dropout when the card is initially inserted into an activated system.
The foregoing objects are achieved as is now described. A circuit card capable of live insertion into an activated electronic system includes a terminal edge from which an edge connector extends a first length. An input decoupling capacitance resides across the edge connector. A backplane within the activated electronic system receives the circuit card, wherein the backplane includes at least one voltage plane, a backplane receptor, and card guide receptor means. The backplane receptor electrically couples the edge connector to the voltage plane when the edge connector engages the backplane receptor. Card guide means are provided for guiding and connecting the circuit card into the backplane, and include at least one conductive member for engaging the card guide receptor means. The conductive member extends a second length from the terminal edge, wherein the second length is greater than the first length. At least one conductive path electrically couples the conductive member across the input capacitance. A voltage supply applied to the card guide receptor means ensures that during insertion of the circuit card into the backplane, but prior to the backplane receptor engaging the edge connector, the input capacitance will pre-charge through the conductive member, thereby preventing arcing and voltage dropout.